(a) Field of the Invention
The present invention relates to a fast wideband frequency comparator.
(b) Description of the Related Art
As next generation mobile communication systems continue to progress, systems that operate faster and in a broadband range are being actively developed. Thus, much research is being conducted on technologies for quickly generating a clock signal and quickly finding a desired band. One of the essential parts of this research is a frequency comparator.
A conventional frequency comparator will be discussed below.
The conventional frequency comparator compares the frequency of a target signal with the frequency of a reference signal to determine whether the frequency of the target signal is fast or slow. To this end, two counters are used to compare the frequencies of two signals. The first counter operates using a target signal as a clock signal, and the second counter operates using a reference signal as a clock signal. When one of the two counters reaches a preset value, a comparison process using the comparator is performed to output a corresponding comparison signal.
In the case of frequency comparison using these counters, however, it takes several tens of microseconds to obtain a comparison result of the frequencies of two signals, which is quite long. Moreover, it is necessary to increase the number of counter bits for higher comparison accuracy. Therefore, the conventional frequency counter is not appropriate for a wireless communication system requiring fast operations.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.